The liquid crystal display device sandwiches a liquid crystal display element between a pair of glass substrates or the like, and is an indispensable device for everyday life and business, such as a car navigation system, an electronic book, a photo frame, industrial equipment, a television, a personal computer, a smart phone, and a tablet terminal, by making the most of its features such as thinness, light weight, and low power consumption. In these applications, liquid crystal display devices of various modes relating to the electrode arrangement for changing the optical characteristics of the liquid crystal layer and the design of the substrate are studied.
Display modes of liquid crystal display devices in recent years include a vertical alignment (VA) mode such as a multi-domain vertical alignment (MVA) mode of vertically aligning liquid crystal molecules having negative anisotropy of dielectric constant with the substrate surface, an in-plane switching (IPS) mode of horizontally aligning liquid crystal molecules having positive or negative anisotropy of dielectric constant with the substrate surface to apply a lateral electric field to the liquid crystal layer, and a fringe field switching (FFS) mode.
Among them, the FFS mode is a liquid crystal mode widely used in smartphones and tablet terminals in recent years. An FFS mode liquid crystal display device including, for example, first and second transparent insulating substrates arranged to face each other at a predetermined distance via a liquid crystal layer containing multiple liquid crystal molecules, multiple gate bus lines and data bus lines formed on the first transparent substrate and arranged in a matrix form so as to define unit pixels, a thin-film transistor provided at an intersection of the gate bus line and the data bus line, a counter electrode disposed in each of the unit pixels and made of a transparent conductor, multiple upper part slits and lower part slits arranged to be insulated from the counter electrode in each unit pixel so as to form a fringe field together with the counter electrode and arranged at a predetermined inclination so as to be symmetrical about the long side of the pixel, and a pixel electrode made of a transparent conductor is disclosed (for example, see Patent Literature 1).
In addition, a liquid crystal display device including upper and lower substrates and a liquid crystal layer sandwiched between the upper and lower substrates, the lower substrate including electrodes, the electrodes including a first electrode, a second electrode in a layer different from the first electrode, and a third electrode in the same layer as the second electrode, the liquid crystal layer including liquid crystal molecules horizontally aligned with respect to the main surface of the upper and lower substrates during voltage non-application, the liquid crystal display device configured to perform a driving operation of causing the electrodes to generate an electric field which rotates some of the liquid crystal molecules in a horizontal plane with respect to the main surface and rotates others of the liquid crystal molecules in a direction opposite to the direction of some of the liquid crystal molecules in a horizontal plane with respect to the main surface, is disclosed (for example, see Patent Literature 2).